Collaborative projects in the environmental health sciences includes those projects in which the mass spectrometry work-group collaborates with other groups, both within and without the Institute to solve problems of mutual interest. The major focuses of these projects are 1) the structure determination of biological compounds of unknown structure, 2) identification and/or confirmation of biological pathways and 3) development of strategies for the structure determination of biologically important compounds. Major projects currently under investigation include; 1) the structure determination of the small peptides expressed by cells infected with flu virus that cause the cell to be recognized by T-cells as being infected (a model of HIV infection). A new collaboration which is in the formative stage is aimed at identifying immunologically important peptides that might be implicated in the abnormal autoimmune response in Lupus mice; 2) the development of combined LC/EPR/MS techniques for the identification of spin-trapped free radicals. This latter project involves the structure determination of chemically produced free-radicals and of free-radicals produced as intermediates in enzymatic processes in biological systems; 3) the effect of visible light on serotonin production with seasonal depressives (a disorder that primarily (80%) effects women).